The present invention relates generally to plastic films and containers made from same. More specifically, the present invention relates to containers for housing medical products and methods for manufacturing same.
It is known to house medical solutions in flexible containers constructed from plastic films. These containers can be used to house products such as parenteral, enteral, and dialysis solutions. Indeed, a great variety of different solutions can be housed and stored in such containers.
A number of issues are raised with respect to the containers for housing medical solutions, and the films that are used to construct such containers. These containers must be constructed so that they do not include harmful extractables that will leach out into the solution. This is especially important with respect to solutions such as parenteral solutions that are infused directly into the bloodstream of the patient.
Further, these containers must be able to stand up to certain rigors of use that other containers do not face due to environments in which they are used. Additionally, issues such as sterility and cleanliness, that may not be as critical with respect to containers used for non-infused solutions create manufacturing as well as product design issues for medical containers.
In fact, the products that are stored in the container themselves can create manufacturing, storage, and container design issues. There are a number of products that due to stability, compatibility, or other concerns must be stored in component parts, such as in separate containers, and admixed before use. This may be due to incompatibility of the products, for example, amino acids and dextrose solutions, or may be due to the fact that certain products must be maintained at different pHs from each other during sterilization or other processing, for example dextrose. Thus, it is known to provide multi-chambered containers. These containers include means by which the separate chambers can be placed in fluid communication with each other allowing the solutions from each of the separate chambers to be intermixed within the container and then administered to the patient.
Multi-chambered containers are much more desirable than storing the components in separate containers and then mixing same together. In part because the process of opening and mixing separate containers can compromise the sterility of the system. Further, the step of opening and mixing separate container creates a labor intense process. Accordingly, to deal with the disadvantages of separate containers, it is known to provide containers having an interior including two or more chambers. One way to create such a container is with a heat seal dividing the interior into two chambers. Such containers are disclosed, for example, in U.S. Pat. Nos. 4,396,488; 4,770,295; 3,950,158; 4,000,996; and 4,226,330.
For example, it is also known to use frangible valves across the heat seal to allow for the selective communication and mixing of the components stored in the separate chambers. See, for example, U.S. Pat. No. 4,396,488.
However, such structures—frangible valves—may not be desirable for a number of reasons including, inter alia, cost. An alternative to frangible valves is disclosed in U.S. Pat. Nos. 3,950,158; 4,000,996; and 4,226,330. In these patents, multiple chamber containers are disclosed with a line of weakness, such as a score line, which breaks upon the application of pressure.
It is also known to provide a selectively openable seal between two sheets of flexible thermoplastic material. U.S. Pat. No. 4,770,295 provides a seal line that is resistant to unintentional opening forces, but opens upon the application of a specific force. The container includes two sheets that form the exterior of the container and an inner diaphragm sheet between the outer sheets. A selectably openable seal is disposed between one of the outer sheets and the diaphragm sheet. A permanent line of securement is preferably included between the exterior sheet and the diaphragm sheet extending substantially parallel to and coextensive with the openable seal line.
In addition, tear tabs or tear strips for plastic packaging are also known such as shown in U.S. Pat. No. 2,991,000. These tear tabs can be used to provide access to the contents of the container. However, a disadvantage with these containers is that they involve the use of relatively complicated seal structures. U.S. Pat. No. 3,983,994 also discloses a seal broken by pulling upon tabs located outside the container.
Another issue that must be considered in constructing containers for the medical industry is that the solutions, and therefore the containers, often require sterilization after the manufacture of the container and/or introduction of the solution. Typically, the products are sterilized by steam sterilization or autoclaving. Autoclave sterilization can alter the thermal properties of the film used to form the container and the seal between the chambers of the container.
Of course, it is necessary in providing a multiple chamber container that the seal between the chambers is capable of withstanding external stresses encountered in normal handling, so that the seal is not prematurely opened. Such stresses include pressure that may be applied to one or more chambers from, for example, squeezing thereof incidental to packaging, or accidental dropping of the bag.
However, a difficulty in creating such a seal, using these types of materials is that the strength of the seal typically increases as a result of the heat applied during sterilization. As a result the seal may be too strong after the sterilization process making it difficult for the end user to separate or open the seal to combine the components within the chambers.
It is relevant to note that the end user of many of the medical solutions contemplated for use with the present invention is often the patient him or herself. This is particularly true in the case of the container being used to contain and administer solutions for peritoneal dialysis. Peritoneal dialysis is an alternative method to traditional hemodialysis by which a patient having end stage renal disease essentially treats him or herself by self-administering dialysis solutions a few times each day. However, patients undergoing dialysis tend to be elderly, often also diabetic, with poor eyesight and substantial weakness and diminished dexterity. Therefore, it is crucial that the force required to open the seal between chambers be carefully controlled to withstand normal handling and a certain amount of accidental jostling, yet not so great as to be difficult for such a patient to readily break when required to do so.
U.S. Pat. No. 5,577,369 discloses a flexible container including a plurality of internal compartments separated by a seal. At least the seal region is constructed from a film that comprises at least two layers, one of which is RF-responsive and the other layer, the inner layer, being non RF-responsive. The RF-responsive layer, in response to RF energy heats the non RF-responsive interior layer to form a peelable seal that is defined by a bonding between the non RF-responsive layers that define the interior of the container.
U.S. Pat. No. 5,209,347 discloses an internal tear seal container having at least two chambers. A selectively openable seal line is provided connecting two sheets of material. The selectively openable seal line is resistant to unintentional opening but opens upon the application of a specific force.